This invention relates to a method and apparatus for installing a centrifugal master clutch into a vehicle.
Typically, a normally open clutch assembly includes a rotating input member such as a flywheel, that selectively engages one or more friction discs. The friction discs transmit rotation from the flywheel by one or more pressure plates. A transmission input shaft is driven by rotation of the friction discs. A plurality of centrifugal weights are pivotally mounted to move radially outward in response to rotation of the clutch assembly. As the rotational speed of the clutch assembly increases, rollers on the centrifugal weights are forced up a ramped surface to force engagement of the pressure plates with the friction discs and transmit rotational drive to the input shaft.
Installation of a clutch assembly requires proper alignment between the friction discs and the flywheel. Normally closed clutch assemblies use a biasing force that normally clamps the pressure plates against the friction discs to maintain proper alignment during assembly. Disadvantageously, a normally open clutch assembly does not clamp the friction discs until the centrifugal weights are driven outward by rotation of the clutch assembly. Therefore, the friction discs are not held in a desired aligned position during assembly. Some other alignment method is thus necessary for a normally open clutch assembly.
One example alignment device for normally open clutch assemblies include cammed sleeves that are inserted within the clutch assembly to hold the centrifugal weights in a position where the pressure plates hold the friction plates in proper alignment with the flywheel.
The cammed sleeves are costly and time consuming to install and produce. Another known-alignment device utilizes shear pins to retain the centrifugal weights in a desired position. Once the clutch is installed in a powertrain it may be necessary to run the engine at high speeds to make the clutch operational. The high speeds cause the shear pins to break such that the clutch becomes operational. Typically, the end customer of the vehicle receiving the clutch may prefer that the engine be limited to less than full operating speed while at stand still during a normal vehicle operating mode. Limiting engine speed is a common feature for powertrains incorporating progressive shift and vehicle speed sensor anti-tampering. Unfortunately, the limited engine speed may be below what is required to make the clutch operational, for example, below the speed at which the shear pins will break.
Customers typically have the preference of performing powertrain configuration in a different area than where the powertrain is installed onto the chassis. What is needed is a method and apparatus for overriding the normal vehicle operating mode once the powertrain is installed onto the chassis.